Raman Spectroscopy and X-ray Diffraction Studies of Stress Effects in PbTiO3 Thin Films

The evolution of domain structure and in-plane and out-of-plane lattice parameters in PbTiO₃ (PTO) films on SrTiO₃ (STO), LaAlO₃ (LAO) and MgO substrates was studied as a function of film thickness and temperature by X-ray diffraction (XRD). Microstrains and average grain sizes were determined in several crystallographic directions for films of different thicknesses using a Williamson-Hall and Langford analysis. Stress relaxation with film thickness was observed in different domains by Raman spectroscopy and greatly influences lattice parameters. Specific contributions of a-and c-domains on Raman spectra were analyzed and correlated to domains fraction. The high temperature structural phase transition was followed by Raman spectroscopy, showing that the transition depends on the nature of stress.